1. Field of the Invention
The embodiments disclosed herein relate to transistors and, more particularly, to a transistor (e.g., a bipolar junction transistor (BJT) or a heterojunction bipolar transistor (HBT)) with narrow in-substrate collector region for reduced base-collector junction capacitance Cbc and to a method of forming the transistor.
2. Description of the Related Art
For transistors used in radio frequency (RF) applications (e.g., bipolar junction transistors (BJTs) and, particularly, for high performance heterojunction bipolar transistors (HBTs)), it is desirable to have a relatively high transit frequency fT and a relatively high maximum oscillation frequency fmax. fmax is a function of fT and also of various parasitics, including parasitic resistances and parasitic capacitances. One such parasitic capacitance is from base-collector junction capacitance Cbc. Reduction of this base-collector junction capacitance Cbc can result in a higher fmax. Thus, it would be advantageous to provide a transistor, such as a bipolar junction transistor (BJT) or heterojunction bipolar transistor (HBT), with reduced base-collector junction capacitance Cbc as well as a method for forming such a transistor.